1. Field of the Invention
The present invention relates to suction cups and, more particularly, to suction cups with a valve for relieving the below ambient pressure.
2. Description of Related Art
Suction cups made of various flexible materials, whether natural or man made, include a spherical concave side in the cup element. Upon pressing the concave side against a smooth impermeable surface, the air within the concavity is forced outwardly past the perimeter of the suction cup. The natural tendency of the suction cup is to rebound but such rebounding is precluded by the ambient pressure being greater than the pressure present in the volume defined between the surface and the concave side. The conventional manner for releasing a suction cup is that of lifting the perimeter of the cup element to permit air flow into the volume or space between the suction cup and the underlying surface. Another, less elegant, way of removing a suction cup from a surface is that of forcibly pulling upon the stem of the suction cup to overcome the pressure differential between ambient pressure and the pressure within the volume or space between the suction cup and the underlying surface.
The inconvenience of existing suction cups is evident in automotive applications where suction cups have been used to hold sheets of sunshade materials adjacent a window. Release of such suction cups may require the use of two hands or at least looking at the suction cup of the sunshade when relocating it. Such distractions to the driver are not only inconvenient but potentially life-threatening.